Processes for the carbonylation of olefinically or alkynically unsaturated compounds in the presence of a hydroxy compound, an acid or water are well-known, and have been described e.g. in European Patent No. 0,055,875, European Patent No. 0,106,379, European Patent No. 0,168,876 and European Patent No. 0,186,228, in which process a palladium catalyst system is employed. Generally such a process is conducted by introducing the various reactants and the catalyst into the reactor and allowing the carbonylation reaction to proceed under the desired conditions. Frequently the reaction medium includes a solvent to promote the solubility or miscibility of the reactants and/or to reduce the viscosity of the reaction medium.
With one of these types of carbonylation processes, i.e. the carbonylation of olefinically unsaturated compounds in the presence of water, it was observed that sometimes the rate of reaction, as measured by the degree of conversion of the olefin reactant within a given time, was reduced to an unacceptably low level.
An investigation carried out by the Applicant into the cause of the reduction in the rate of reaction, indicated that said phenomenon could well be related to formation of a reaction medium having more than one liquid phase, hereinafter referred to as multi-phase liquid reaction medium, as a result of insufficient miscibility of the liquid olefin or alkyne reactant and water, even when said reaction medium included a solvent.
The problem underlying the present invention is developing a process for the carbonylation of olefins or alkynes with carbon monoxide and in the presence of water, which does not suffer from the disadvantage as mentioned hereinbefore.
As a result of extensive research and experimentation it was found that the carbonylation of olefins or alkynes with carbon monoxide in the presence of water and a multi-phase liquid reaction medium, can advantageously be conducted in the presence of palladium catalyst compositions which include selected substituted phosphine ligands.